The present invention concerns a method for securing a jaw die plate of a jaw crusher detachably against the front end wall of a jaw crusher. The invention also concerns a jaw crusher.
The stationary jaw die plate or plates of a jaw crusher are conventionally secured to the front end wall or front frame of the crusher, by fastening them by bolting through said end wall. The jaw die plate is pressed against the front end wall by means of a wedge, a recess made to an aperture of said wedge receiving the head of the fastening bolt. Usually, so called hammer-type bolts are used as fastening bolts. The jaw die plate can be divided vertically into two or more separate wearing parts.
For mounting a stationary jaw die plate to the crusher, there must be space provided in front of the front end wall of the crusher. Often the problem is that the required space is not available, but immediately in front of the crusher there are e.g. supporting structures of the feeding device feeding the crusher, or, provided under the feeding device there is a by-pass chute for the fines, meant for removing the fines from the feed material. These structures must be removed in order to install the jaw die plate, which is time consuming and causes costs and production losses.
Generally, the securing wedges of the jaw die plates are located as extensions to the upper and lower parts of the jaw die plate, so that also the front end wall of the crusher must extend behind the securing wedges. This means that the front end wall of the crusher must be considerably higher than the jaw die plate. The material to be crushed is fed into the opening of the crusher over the front end wall of the crusher, so that in a traditional solution, the feeding device must be unnecessarily high with respect to the jaw die plate which performs the crushing work itself.
Known in the art there are also such securing methods of the jaw die plate, in which the jaw die plate is wedged against the front end wall by means of a side wedge or cheek plate provided respectively on both sides of the jaw. The cheek plate also acts as a protection for the side plate of the crusher. The wearing of the cheek plates, however, is minor compared to the wearing of the crushing jaw die plates, so that the detaching of the cheek plates when changing the jaw die plates is unnecessary work.
Patent publication U.S. Pat. No. 3,984,058 discloses a jaw crusher, in which the jaw die plate is secured by its sides to the side plates of the crusher by means of angle pieces. One end of an angle piece is bolted to the side plate. The surface of the angle piece to be fitted against the side plate is tapered, so that when the bolt is tightened, the angle piece pivots about its vertical corner edge. The end of the angle piece facing towards the side plate is beveled, and when the angle piece turns, it is forced against the bevelled counter surface of the internal cheek plate of the side plate. The other, blunt end of the angle piece is forced against a diagonal counter surface in the recess of the jaw die plate. One component of the securing force arising in this way forces the jaw die plate against the front end wall, and the second component prohibits the lateral movement of the die plate. In this prior art solution, again, the side plate cannot be detached without removing the jaw die plate. This construction requires dimensional accuracy from the joint surfaces as well of the cheek plate as of the jaw die plate. Because these both pieces are made of a very hard material, they are difficult to be machined. That increases the production costs of the components.
In the solution of the present invention, no mounting space is required in front of the front end wall of the crusher. This means that the changing of the jaw die plates is easier. It is not necessary to dismount the feed arrangements or fines removal systems for changing the jaw die plate, so that costs are reduced and production breaks shortened. The front end wall of the crusher can be constructed as low as the stationary jaw die plate and so the feeding level of the material can be lowered. This means a lower, lighter and less expensive crusher unit, as a whole. This is significant especially with mobile and self-propelled crusher units.
Further, the solution in accordance with the invention does not require complicated machining of the jaw die plate, which would be a very expensive operation, as the die plate is manufactured of hard and high-tensile alloy steel.
In the solution of the invention, the jaw die plate is secured to the front end wall of the crusher by means of a mechanism which in the direction of the normal of the surface of the front end wall and the rear surface of the stationary jaw die plate of the crusher, is mainly friction restrained. In other words, the jaw die plate is prevented from loosening from the front end wall by means of a friction force which is parallel to the normal of the surface of the front end wall of the crusher, said friction force being generated between two or a plurality of pressing surfaces by applying thereto a force parallel to the plane of the front end wall of the crusher. Additional security can be provided by using different profiled restraint solutions, the main part of the restraint action, however, being generated by the friction force.